Bug#19392 Rename Database: Crash if case change

Problem:
Renaming a database to itself crashed server.
It hapenned because of wrong DBUG_ASSERT.
Fix: removing wrong DBUG_ASSERT. Now it reports
a correct error message "database alreadt exists".


mysql-test/r/renamedb.result:
  Adding test case
mysql-test/t/renamedb.test:
  Adding test case
sql/sql_db.cc:
  DBUG_ASSERT crashed server when renaming a database to itself.

1 files changed, 3 insertions, 3 deletions

diff --git a/sql/sql_db.cc b/sql/sql_db.cc
index 3d035359b6f..cb43bb77def 100644
--- a/sql/sql_db.cc
+++ b/sql/sql_db.cc
@@ -134,9 +134,9 @@ void lock_db_delete(const char *name, uint length)
 {
   my_dblock_t *opt;
   safe_mutex_assert_owner(&LOCK_lock_db);
-  opt= (my_dblock_t *)hash_search(&lock_db_cache, (const byte*) name, length);
-  DBUG_ASSERT(opt != NULL);
-  hash_delete(&lock_db_cache, (byte*) opt);
+  if (opt= (my_dblock_t *)hash_search(&lock_db_cache,
+                                      (const byte*) name, length))
+    hash_delete(&lock_db_cache, (byte*) opt);
 }